JP2001026774A - Heat storage material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat storage material whose coagulation point and melting point can suitably be operated and which can effectively use the coagulation heat and the melting heat to enable heat storage and release. SOLUTION: This heat storage material is obtained by sealing a core substance accompanying phase changes in fine capsules comprising an organic film substance, and is used a slurry. Therein, the core substance is prepared by mixing two or more aliphatic hydrocarbons having different molecular weights.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat storage material applied to a latent heat storage system and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a heat storage method in a conventional latent heat storage system, for example, an ice heat storage method using water as a heat storage material and utilizing the latent heat of melting and solidification of the water is known. In this method, cold water is stored as ice by cooling water using brine (antifreeze) cooled to 0 ° C. or less during heat storage, and the ice is directly cooled using heat or indirectly through brine during heat radiation. Is melted and the cold heat is taken out.

In the latent heat storage system using the conventional ice heat storage method, when storing heat, brine is cooled to -5.degree.
Because of the need to cool to the extent, it is necessary to lower the refrigerant evaporation temperature of the refrigerator, the ratio of the heat storage amount to the input of the refrigerator, that is, the coefficient of performance is low, and the refrigerant gas specific volume increases due to the decrease in the refrigerant evaporation temperature. As a result, the refrigerating capacity of the same compressor is reduced. In addition, it is necessary to use brine when cooling ice, and care must be taken in its management.

As another example of a latent heat storage system, a latent heat storage material that changes phase at room temperature is utilized, and the latent heat storage material is encapsulated in a capsule or container as a core material to form cold water or water. Cooling as a solid by cooling using brine, or storing heat as a liquid by heating using warm water, and indirectly melting the cold heat by indirectly melting the latent heat storage material during heat radiation, taking out the heat by solidifying Methods are known. When using the latent heat storage material that changes phase at normal temperature, it is necessary to enclose the latent heat storage material in a capsule or container in terms of handling when the latent heat storage material has volatility or when used in a eutectic salt solution. .

On the other hand, as these capsules and containers, spherical ones having a diameter of 70 mm or rectangular or plate-like containers having a side of several tens cm are used, filled in a heat storage tank and used in a stationary state. The space between the heat storage tank and these capsules or containers is filled with water or brine.

In such a stationary capsule system and a container system, during heat storage and heat release, heat transfer between the capsule or container (hereinafter referred to as a heat storage material container) and a heat medium fluid such as water is used. The performance is deteriorated, and the thermal resistance between the wall of the heat storage material container and the latent heat storage material is large. Therefore, the temperature of the latent heat storage material heated at the time of heat release or the temperature difference between the temperature of the latent heat storage material cooled at the time of heat storage and the temperature of the heat medium fluid used, such as water, must be about 5 ° C. or more in each state. Therefore, it is necessary to provide a temperature difference of 10 ° C. or more between the temperature of the heat medium fluid used such as water during heat storage and heat release. That is, when trying to extract cold water of 5 ° C., it is necessary to cool with brine of −5 ° C. when storing heat. Further, if it is attempted to store heat at a temperature level at which brine is not used, the temperature of taking out cold water becomes 10 ° C. or more, which is a temperature which is not directly usable for general air conditioning or the like.

In order to solve the problem of the system using such a latent heat storage method, a microcapsule formed by encapsulating a latent heat storage material as a core material in a microcapsule is mixed with water to form a slurry to form a fluid. (Below,
This slurry is called a microcapsule slurry), and a system with improved heat transfer performance is known. In this system, during heat storage, the microcapsule slurry is directly cooled by exchanging heat with cold water or brine by a heat exchanger, thereby storing cold heat in the latent heat storage material in the microcapsules. Also, at the time of heat release, the microcapsule slurry is returned to the heat exchanger and exchanged heat with cold water or brine to directly heat, thereby extracting cold from the latent heat storage material in the microcapsules.

[0008] In such a microcapsule slurry system, the microcapsules themselves flow and exchange heat with the heat transfer fluid through the heat transfer surface, which is sufficiently higher than the above-mentioned stationary heat storage material container system. The heat transfer coefficient is obtained, and the heat storage / radiation temperature close to the value of a general fluid such as water and close to the melting point and freezing point of the latent heat storage material (the temperature difference between the microcapsule slurry and the fluid used such as water is 0.75 C. to about 3 C.).

Next, looking at the cold heat utilization temperature range, the standard specification temperature of a general large refrigerator is 10 ° C. inlet / 5 ° C. outlet, 12 ° C.
Two temperature zones are used: ° C inlet / 7 ° C outlet. On the air conditioning equipment side, the temperature range is 5 ° C. difference, and the operating temperature range is at most 7 ° C. difference. About district heat supply, 1
2 ° C return / 5 ° C feed, 14 ° C return / 7 ° C feed, 13.5
The heat supply facilities differ depending on the characteristics of the block to which heat is supplied, such as the return of ° C / the feed of 6.5 ° C. In recent years, a large temperature difference air-conditioning system has been adopted in the ice heat storage system, and there is a tendency to reduce various auxiliary machine powers and reduce the diameter of piping equipment, such as 15 ° C return / 2 ° C feed.

[0010] On the other hand, when a latent heat storage material is selected, a phase change temperature range peculiar to each is determined, and there are often problems such as restrictions on use in a new plant.

As described above, in the case of the latent heat storage material for cold heat, in consideration of application to existing facilities and use in a new plant, it is possible to adjust the melting point, the freezing point, and the phase change temperature range according to each need. is necessary.

The microcapsules can be used for hot heat storage as well as cold heat storage by using a latent heat storage material as a core material having a high melting point.

[0013]

In the above-mentioned method of using a latent heat storage material encapsulated in a capsule or a container,
When a pure substance is used as a latent heat storage material (for example, an aliphatic hydrocarbon), the pure substance has a unique freezing point and melting point, so that the freezing point and melting point of the latent heat storage material cannot be freely manipulated. For this reason, a latent heat storage material composed of a mixture is generally used, and the solidification point and melting point of the latent heat storage material are controlled by changing the mixing ratio.

On the other hand, in the above-described method in which a latent heat storage material is encapsulated in a microcapsule, the melting point and freezing point of the material confined in the microspace are in a bulk state, that is, several milliliters.
It differs from the value when the latent heat storage material itself is measured in an open state (milliliter) or more, for example, in a test tube or a beaker. As an example of this phenomenon, the freezing point of a water drop of several μm constituting a cloud or the like in nature is -20 ° C. to −4 ° C.
It is known that a supercooled state as large as 0 ° C. is exhibited. For this reason, even in the case of a pure substance or a mixed substance, there is an engineering problem that the value in the state of use cannot be known unless the test is carried out similarly by microencapsulation.

Further, the melting point and freezing point of the microcapsule are statically determined by a differential scanning calorimeter (DSC).
Scanning Calorimetry) and the value measured with stirring in a slurry in water (hereinafter referred to as
Dynamic test), it is necessary to finally determine the melting point and the freezing point by the dynamic test when configuring the heat storage system. For this reason, the operation of the freezing point and melting point of the latent heat storage material cannot be properly performed.

The solidification and melting of the mixed substance are performed with a certain temperature range with a certain width, and the solidification start point, solidification end point and melting point are determined by using inflection points in the solidification temperature curve or the melting temperature curve. The starting point and the melting end point are defined for convenience. However, melting and solidification may be performed outside the defined solidification start point, solidification end point, melting start point, and melting end point. For this reason, if there is no considerable margin in the operating temperature range, there is a problem that heat storage and heat dissipation cannot be performed effectively using the heat of solidification and heat of fusion of that portion, which is the conventional maximum difference in cold water use temperature. Under existing supply conditions, such as a 7 ° C difference, a latent heat storage material that changes phase in a narrow melting and solidification temperature range is required.

On the other hand, when a latent heat storage material that changes phase in a narrow melting and solidifying temperature range is used, the degree of bending of the temperature-specific enthalpy curve becomes large, and the heat storage cold water and the heat radiation are reduced due to the pinch point in the heat exchanger. The temperature difference of the cold water becomes small, and it is necessary to increase the flow rates of the heat storage cold water and the heat radiation cold water.

A first object of the present invention is to provide a heat storage material capable of appropriately controlling the freezing point and melting point, and capable of storing and releasing heat by effectively utilizing the heat of solidification and the heat of fusion.

A second object of the present invention is to enable the operation of the freezing point and the melting point to be appropriately performed within the cold water design temperature range, and to effectively utilize the heat of solidification and the heat of fusion in a narrow temperature range. An object of the present invention is to provide a heat storage material capable of releasing heat.

A third object of the present invention is to widen the phase change as much as possible for any heat exchanger temperature condition corresponding to the chilled water design temperature range, and to suppress the generation of extreme pinch points in the heat exchanger. An object of the present invention is to provide a heat storage material capable of performing economical heat exchange.

[0021]

Means for Solving the Problems In order to solve the above problems and achieve the object, a heat storage material and a method for manufacturing the same according to the present invention are configured as follows.

(1) The heat storage material of the present invention is a heat storage material used as a slurry in which a core material with a phase change is encapsulated in a fine capsule made of an organic film material. It consisted of a mixture of two or more types of hydrogen.

(2) The heat storage material of the present invention is the heat storage material according to the above (1), and the core material is a mixture of tetradecane and pentadecane, which are aliphatic hydrocarbons, as a main constituent material. 80% of the main constituents
The weight ratio of the tetradecane and the pentadecane is in the range of 30 to 1
Pentadecane is 70% to 90%
By manipulating the weight mixing ratio of the core substance, the freezing point and the melting point were made to correspond to an arbitrary design temperature range. It should be noted that there is an inclusion in the industrial material, and in particular, pentadecane (PD) includes a case where it contains a considerable amount of a molecular weight component higher than PD or a case where it is made of a pure substance regardless of whether or not it is specified.

(3) The heat storage material of the present invention is the heat storage material according to the above (1), and the core material is, as an industrial refined product, mainly composed of aliphatic hydrocarbons tetradecane and pentadecane. The mixture of polymer components is a main constituent, the core constituent has a weight ratio of 80% or more in the core material, and the mixture weight ratio of the tetradecane and the polymer component containing pentadecane as a main component is: The polymer component containing pentadecane as a main component is 70 to 90% while the tetradecane content is 30 to 10%, and the polymer component containing hexadecane or higher is 10 to 15%. The solidification point and the melting point were made to correspond to an arbitrary design temperature range by manipulating the weight mixing ratio of the main constituent substances of the core substance.

(4) The heat storage material of the present invention is the heat storage material as described in (2) above, and the core material is mainly composed of aliphatic hydrocarbons tetradecane and pentadecane as an industrially purified product. A mixture of polymer components is used as a main constituent material, and the main constituent material has a weight ratio of 80% or more in the core material. By adding a high molecular weight hydrocarbon component in addition to the core material, the phase change temperature range is increased. The design temperature range was maximally supported, and the occurrence of extreme pinch points due to the heat exchanger temperature difference was suppressed.

(5) The heat storage material of the present invention is the heat storage material according to the above (2), and the design temperature range is a range from a feed temperature of cold water of 2 ° C. to a return temperature of 15 ° C.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a diagram showing a configuration of a latent heat storage system using a microcapsule slurry as a heat storage material according to a first embodiment of the present invention. . This latent heat storage system is applied to district heating and cooling, and as shown in FIG. 1, a heat storage tank (latent heat storage tank) 1,
It comprises a heat exchanger 2, a slurry circulation circuit 3, a cold water circulation circuit 4, a refrigerator 5 and the like.

The heat storage tank 1 is a vessel containing a microcapsule slurry 11 in which a myriad of microcapsules are mixed with water at a predetermined concentration to form a slurry. Each microcapsule contains
A latent heat storage material that changes its phase at normal temperature and stores latent heat is enclosed as a main constituent of the core material. The latent heat storage materials include aliphatic hydrocarbons (paraffinic hydrocarbons) such as tetradecane (TD) and pentadecane (P
D), and a melamine resin (organic resin) is used as the film of the microcapsules. A mixture of tetradecane and pentadecane accounts for 80% or more of the total weight of the core substance encapsulated in each microcapsule, and a supercooling inhibitor is also added to the core substance. Also, the particle size of one microcapsule is preferably 1-2 μm.
However, if it is about 20 μm or less, it is practical.

The heat exchanger 2 is connected to the heat storage tank 1 via a slurry circulation circuit 3 having a slurry pump 6. Further, an evaporator 51 in the refrigerator 5 is connected to the heat exchanger 2 via a chilled water circulation circuit 4 having a chilled water pump 8.

Therefore, during heat storage and heat release, the slurry pump 6 is operated to supply the microcapsule slurry 11 in the heat storage tank 1 to the heat exchanger 2 through the slurry circulation circuit 3. The chilled water pump 7 or the chilled water pump 8 is operated to supply chilled water to the heat exchanger 2 through the chilled water circulation circuit 4. Thereby, heat exchange can be performed between the microcapsule slurry 11 and the cold water in the heat exchanger 2.

For example, when storing cold heat at night, the heat storage tank 1
Of the microcapsule slurry 11 taken out of the heat exchanger 2
Is cooled by exchanging heat with cold water of 3.5 ° C. cooled by a refrigerator. When the latent heat storage material of each microcapsule changes to a solid phase, the heat is stored in the heat storage tank 1. By continuing this circulation, the inside of the heat storage tank 1
The latent heat storage material of the microcapsules is replaced by the microcapsule slurry that has changed to the solid phase, and the heat storage is completed.

At the time of cooling heat radiation in the daytime, the slurry circulation circuit 3 is switched to supply the microcapsule slurry 11 in which the latent heat storage material of each microcapsule has changed to a solid phase to the heat exchanger 2. The heat exchanger 2 switches the chilled water circulation circuit 4 to exchange heat between the returned chilled water (12 ° C.) from the load side and the microcapsule slurry, thereby converting the cryogenic heat generated when the latent heat storage material of the microcapsules changes to the liquid phase. Give to cold water. This cold water is supplied to the load side as feed cold water (5 ° C.). The temperature of the microcapsule slurry 11 in which the latent heat storage material of the microcapsules has changed is raised and returned to the heat storage tank 1.

The refrigerator 5 is operated using inexpensive electric power at night, and cool water generated by the evaporator 51 is supplied to the heat exchanger 2.
Supply to The heat taken by the evaporator 51 is transferred to the compressor 5
The pressure is increased by 2 and is discarded from the cooling tower 9 via the condenser 53.

As shown in FIG. 1, when the temperature of the feed chilled water is 5 ° C. and the temperature of the returned chilled water is 12 ° C. at the time of heat radiation, the microcapsules supplied to the heat exchanger 2 pass through the heat exchanger 2. When a temperature difference (design value) of about 0.75 ° C. is set between the temperature of the slurry and the temperature of the feed cold water, and between the temperature of the microcapsule slurry returned from the heat exchanger 2 and the temperature of the return cold water, respectively ( In this case, the design value indicates the minimum temperature difference, and it is not always necessary to make them equal on the entrance and exit sides.) The temperature of the microcapsule slurry supplied from the latent heat tank 1 to the heat exchanger 2 is 4.25 ° C. The temperature of the microcapsule slurry returned from 2 to the latent heat tank 1 is 11.25 ° C.

In the above case, the phase change from the solid phase to the liquid phase or from the liquid phase to the solid phase in the latent heat storage material in the microcapsule is ideally performed between 4.25 ° C. and 11.25 ° C. is there. However, since the phase change occurs with a temperature range, unmelted components may remain in a temperature range higher than 11.25 ° C., or unsolidified components may remain in a temperature range lower than 4.25 ° C.

For this reason, 4.25 in the latent heat storage material
Comparing the measured value between 1 ° C. and 11.25 ° C. with the theoretical value,
The amount of heat indicated by the measured value (latent heat amount + sensible heat amount) is smaller than the amount of heat indicated by the theoretical value (total latent heat amount + sensible heat amount). Also, in the microcapsule slurry state, the freezing point of the latent heat storage material is different from that measured in the bulk state of the latent heat storage material alone, so if the mixing ratio of the latent heat storage material is not appropriate for the design temperature range, the measured value The difference between the theoretical values becomes even more pronounced.

Hereinafter, the ratio of the measured value of the sensible heat to the latent heat storage material of the microcapsule slurry 11 when the phase change of the latent heat storage material from the solid phase to the liquid phase or from the liquid phase to the solid phase and the theoretical value is calculated as the phase change efficiency η. And is defined as the following equation.

Η = (QS + QL) M / (QST + QLT) Here, (QS + QL) M indicates the measured value of the amount of heat due to sensible heat and latent heat, QST is the theoretical value of sensible heat, and QLT is the entire temperature range of latent heat. It shows the theoretical value of the calorific value (the temperature range is wide with the static total calorific value of the microcapsule measured by DSC or the like).

When the measured value (dynamic state) of the calorific value in the microcapsule slurry matches the theoretical value,
The phase change efficiency η = 1. However, a deviation occurs between the measured value and the theoretical value, and η <1. This is because the measured value of latent heat calorie obtained along the process of phase change in a certain temperature range is different from the theoretical value of latent heat calorie obtained by differential scanning calorimeter of phase change in a sufficiently wide temperature range. To come.

Therefore, in order to improve the phase change efficiency, it is necessary to appropriately control the melting point and the freezing point. This operation can be performed by optimizing the mixing ratio of the latent heat storage material in the microcapsule slurry state (dynamic state).

FIGS. 2A and 2B are graphs showing the measurement results of the phase change temperature in the microcapsule slurry. FIG. 2A shows an example of the result of measuring the melting point of the microcapsule slurry, and shows the temperature response during heating. In this measurement, a microcapsule slurry in which a latent heat storage material is completely solidified is placed in a thermostat, and the temperature change of the microcapsule slurry is measured. As shown in the figure, the temperature of the microcapsule slurry increases with time, but in a certain temperature range, the temperature rise becomes gentle, and the latent heat storage material is melted in that temperature range. Here, when trying to define the inflection point as the melting start point and the melting end point, since the inflection point at the start of melting is unclear, the intersection of each extension line of the straight line before and after that is defined as the melting start point. . Therefore, even at a temperature lower than the defined melting start point (temperature), a certain amount of melting is performed.

On the other hand, FIG. 2B shows an example of the result of measurement of the freezing point of the microcapsule slurry, showing the temperature response during cooling. In this measurement, a microcapsule slurry in which a latent heat storage material is completely melted is placed in a thermostat, and the temperature change of the microcapsule slurry is measured. As shown in the figure, the temperature of the microcapsule slurry decreases with time, but in a certain temperature range, the temperature decreases gradually, and the latent heat storage material solidifies in that temperature range.
Here, when trying to define the inflection point as the solidification start point and the solidification end point, the inflection point at the end of solidification is unclear, so the intersection of each extension line of the straight line before and after that is defined as the solidification end point. .
Therefore, even at a temperature lower than the defined solidification end point (temperature), a certain amount of coagulation continues.

FIG. 3 is a diagram showing the relationship between the temperature and the specific enthalpy in the microcapsule slurry. As shown in the figure, the specific enthalpy of the microcapsule slurry increases as the temperature rises, but the temperature rise is slow in a certain temperature range, and the latent heat storage material is melted in the temperature range. Further, as the specific enthalpy increases, the temperature rise increases rapidly, and the relationship between the temperature and the specific enthalpy is proportional.

As described above, the melting and heat radiation of the microcapsule slurry have a certain temperature range, and the phase change efficiency is increased by setting the temperature range to be within the design temperature range. The latent heat can be used effectively.

As described above, the characteristics of the microcapsule slurry and an example of the system configuration have been described. Next, a specific embodiment using the phase change efficiency η as an index will be described.

FIG. 4 is a diagram showing the correlation between the mixing ratio of tetradecane (TD) and pentadecane (PD) or higher components and the phase change efficiency in the following three examples. In FIG. 4, the mixing ratio (%) of tetradecane is set to 100 at the left end of the horizontal axis, and gradually decreased to 0 at the right end. Further, the mixing ratio (%) of the pentadecane or higher component was set to 0 at the left end of the horizontal axis, gradually increased, and increased to 1 at the right end.
00 is set. On the horizontal axis, the sum of the mixing ratio of tetradecane and the mixing ratio of components higher than pentadecane is always 10%.
0%. The vertical axis indicates the phase change efficiency in the design temperature range. The melting point of each pure substance is 5.9 ° C. for tetradecane and 9.9 ° C. for pentadecane.

(First Embodiment) The first embodiment is an example in which the heat storage design temperature range is 7 ° C. difference from 4.25 ° C. to 11.25 ° C. in the microcapsule slurry. Indicated by The minimum temperature difference in the heat exchanger during heat release is 0.7
When the temperature is set to 5 ° C, the difference in the use temperature of cold water etc. is 5 ° C to 12 ° C
7 ° C. difference. The heat storage chilled water temperature at the design minimum temperature difference of this heat exchanger is 3.5 ° C at the inlet and 10.5 ° C at the outlet.
This is a range that can be dealt with by a general cold water refrigerator.

The point at which the phase change efficiency becomes maximum in this temperature range is a mixture ratio of 80% or more of PD to 20% of TD,
%. Next, characteristics when the mixing ratio of PD-TD is changed in the heat storage design temperature range of the microcapsule slurry will be described. When the TD concentration is increased to 30% and the PD concentration is decreased to 70%, both the melting point and the freezing point of the latent heat storage material in the microcapsules decrease, and the unsolidified component increases at the temperature lower limit of 4.25 ° C of the microcapsule slurry during heat storage. As a result, the phase change efficiency decreases. Conversely, T
When the D concentration is decreased to 10% and the PD concentration is increased to 90%, the unmelted component increases at the upper limit temperature of the microcapsule slurry of 11.25 ° C. during heat radiation, and phase change substances in the microcapsules contributing to the phase change are apparent. And the phase change efficiency also decreases.

As described above, when the heat storage design temperature range of the microcapsule slurry is in the range of 4.25 ° C. to 11.25 ° C., the unsolidified component at the lower limit temperature of 4.25 ° C. and the upper limit temperature of 11.25 ° C.
The PD-TD mixture ratio at the point where the unmelted component at 25 ° C. is the smallest, that is, the point where the phase change efficiency is the highest is PD80.
% -TD was obtained from the calorimetric test results of the microcapsule slurry shown in FIG.

The heat storage utilization temperature is determined by the design minimum temperature difference of the heat exchanger with respect to the design temperature difference of the heat storage of the microcapsule slurry. In order to suppress the cost of the heat exchanger, the design minimum temperature difference of the heat exchanger is, for example, 1 When the temperature is set to 0.5 ° C., the temperature condition of cold storage or the like used for storing cold water is 2.75 ° C. at the inlet and 9.75 ° C. at the outlet when storing heat. 5.75 ° C at inlet and outlet at 75 ° C.

As described above, there is a one-to-one dependency between the heat storage design temperature range of the microcapsule slurry at which the phase change efficiency is maximized and the mixing ratio of the latent heat storage material in the microcapsules.
The heat storage utilization temperature range of the cold water or the like can be arbitrarily set according to the design conditions of the heat exchanger.

(Second Embodiment) In the second embodiment, the heat storage design temperature range of the microcapsule slurry is from 2.25 ° C. to 9.2.
This is an example in the case of a 7 ° C. difference of 5 ° C.
Indicated by The point at which the phase change efficiency is maximum in this temperature range is P
It can be seen that the mixing ratio is 70% of TD or more and 30% of TD. When the TD-PD ratio is increased or decreased by 10% in the same manner as in the first embodiment, the phase change efficiency decreases.

The use temperature range of the cold water or the like of the second embodiment is as follows.
Assuming that the minimum temperature difference of the heat exchanger is 0.75 ° C., the temperature conditions for cold water during heat storage are 1.5 ° C. at the inlet and 8.5 ° C. at the outlet.
This is lower than a general chilled water refrigerator specification, but it can be said that a chilled water supply compatible machine with a large temperature difference can handle it. On the other hand, as the temperature condition of cold water at the time of heat release, 10.0 ° C.
3.0 ° C. is obtained at the outlet.

(Third Embodiment) In the third embodiment, the heat storage design temperature range of the microcapsule slurry is from 13.25 ° C to 13.30 ° C.
This is an example in the case of a 7 ° C. difference of 25 ° C., which is indicated by c in FIG. The point where the phase change efficiency is maximum in this temperature range is
It can be seen that the mixing ratio is PD 90% -TD 10%. In this case, the maximum phase change efficiency reaches 94-95%. When the TD-PD ratio is similarly increased or decreased by 10% with respect to this mixture ratio, the phase change efficiency decreases.

The use temperature range of the cold water or the like of the third embodiment is as follows.
Assuming that the minimum temperature difference of the heat exchanger is 0.75 ° C., the temperature conditions for cold water during heat storage are 5.5 ° C. at the inlet and 12.5 ° C. at the outlet.
° C is obtained.
° C., 7.0 ° C. at the outlet.

(Fourth Embodiment) The fourth embodiment is an example in which the design temperature range of heat storage is 9 ° C. difference from 2.25 ° C. to 11.25 ° C. in the microcapsule slurry. Indicated by The minimum temperature difference in the heat exchanger during heat release is 0.7
When the temperature is 5 ° C, the temperature difference between cold water etc. is 3 ° C to 12 ° C
Of 9 ° C. The heat storage chilled water temperature at the design minimum temperature difference of this heat exchanger is 1.5 ° C at the inlet and 10.5 ° C at the outlet.
This is lower than a general chilled water refrigerator specification, but it can be said that a chilled water supply compatible machine with a large temperature difference can handle it.

Next, the characteristics when the mixing ratio of PD-TD is changed in the designed temperature range of the accumulation of the microcapsule slurry will be described. Comparing at a mixing ratio of PD 80% -TD 20%, the heat storage design temperature of the first embodiment was 4.25 to 1
For a 1.25 degree 7 ° C. difference, the phase change efficiency is 96
It can be seen that the value exceeds%. This is considered to be due to the fact that the latent heat storage amount of the unsolidified component was added between 2.25 ° C. and 4.25 ° C. in the case of the difference of 7 ° C. in the first embodiment. Next, when the TD concentration is increased to 30% and the PD concentration is decreased to 70%, both the melting point and the freezing point of the latent heat storage material in the microcapsule are lowered.
It can be seen that the phase change efficiency is slightly larger than the case of the difference of 7 ° C. from 25 ° C. to 9.25 ° C. This is because the latent heat storage amount of the unmelted component between 9.25 ° C. and 11.25 ° C. was added to the difference of 7 ° C. in the second embodiment.

As described above, the phase change efficiency is increased by setting the thermal storage design temperature range of the microcapsule slurry wide.

As described above, the supply chilled water temperature range from 4 ° C. (minimum 2 ° C.) to 14 ° C. (maximum 15 ° C.), which is expected to be used for arbitrary district cooling and heating facilities and air conditioning. The highest phase change efficiency can be obtained by determining the microcapsules having the respective optimum mixing ratios within the design temperature range of cold water or the like.

The weight mixing ratio of the tetradecane component in the microcapsule shown in the first embodiment is as follows:
98% of tetradecane as a main component and 2% of tridecane (low melting point paraffin) and the like. The weight mixing ratio of the components of pentadecane is 86% for pentadecane as a main component, 12% for hexadecane, 1% for tetradecane (high melting point paraffin), and 1% for others. Further, as the film of the microcapsule, an organic resin such as polyamide or styrene can be used in addition to the melamine resin.

(Fifth Embodiment) FIG. 5A shows a latent heat storage material which has a large weight ratio of a latent heat storage material which is a main constituent material of a core material of a microcapsule slurry and changes phase in a narrow melting / solidification temperature region. Fig. 3 shows the relationship between the temperature of a used microcapsule slurry in a heat exchanger and the specific enthalpy. In the curve showing the relationship between temperature and specific enthalpy,
The latent heat region where the temperature change is small with respect to the increase in the specific enthalpy, and the temperature change with the increase in the specific enthalpy is approximately 1:
The distinction of the sensible heat region which is 1 appears. When the weight ratio of the latent heat storage material, which is the main constituent in the core material of the microcapsule slurry, is high, the distinction between the latent heat region and the sensible heat region is clearly apparent.

FIG. 5B also shows the temperature of the cold storage water at a position corresponding to the specific enthalpy of the microcapsule slurry during heat storage. The solidification start point of the microcapsule slurry is a pinch point close to the temperature of the heat storage cold water, indicating that the outlet temperature of the heat storage cold water cannot be raised any further.

On the other hand, FIG. 5C also shows the temperature of the radiating cold water at the position corresponding to the specific enthalpy of the microcapsule slurry during heat radiation. The vicinity of the heat radiation start point of the microcapsule slurry is a pinch point close to the temperature of the heat radiation cold water, which indicates that the temperature of the heat radiation cold water outlet cannot be further reduced.

FIG. 6A shows that the phase change occurs in a wide melting / solidification temperature range when the weight ratio of the latent heat storage material, which is the main constituent of the core material of the microcapsule slurry, is small, or when other molecular weight inclusions are mixed. FIG. 3 shows the relationship between temperature and specific enthalpy in a heat exchanger of a microcapsule slurry using a latent heat storage material adjusted to a specific temperature. In the curve showing the relationship between the temperature and the specific enthalpy, the distinction between the latent heat region and the sensible heat region is not clear, and the phase change is wide and gentle.

FIG. 6B also shows the temperature of the heat storage cold water at a position corresponding to the specific enthalpy of the microcapsule slurry during heat storage. Since the solidification start point of the microcapsule slurry changes gradually, the temperature difference between the heat storage cold water temperature and the pinch point close thereto is larger than that in FIG. 5, indicating that the cold water outlet temperature can be increased. on the other hand,
FIG. 6C also shows the temperature of the cooling water at the position corresponding to the specific enthalpy of the microcapsule slurry during heat radiation. Since the vicinity of the heat radiation start point of the microcapsule slurry changes gradually, the pinch point close to the heat radiation cold water is lower than that in FIG. 5, indicating that the heat radiation outlet temperature can be lowered.

As described above, the phase change range of the temperature-specific enthalpy curve of the microcapsule slurry is obtained by mixing other molecular weight inclusions with the latent heat storage material, which is the main constituent material of the core material of the microcapsule slurry. By widening and changing the latent heat area and sensible heat area smoothly, the pinch point temperature difference between the heat storage cold water and the heat radiation cold water of the heat exchanger can be increased, without causing an extreme drop in the logarithmic average temperature difference. It is possible to increase the economical efficiency of the heat exchanger and to make the outlet temperature of the regenerative cold water and the outlet temperature of the radiating cold water close to the inlet temperature of the microcapsule slurry.

The present invention is not limited to the above embodiments, but can be implemented with appropriate modifications without departing from the scope of the invention.

(Summary of Embodiment) In the present embodiment, in the latent heat storage system using the microcapsule slurry, the latent heat storage material is mainly composed of aliphatic hydrocarbons tetradecane and pentadecane. Then, for the cold water design temperature range where the temperature of the feed cold water is 4 ° C. (minimum 2 ° C.) to 7 ° C. and the temperature of the return cold water is 12 ° C. to 14 ° C. (maximum 15 ° C.), tetradecane: 30% to 10%
%, Pentadecane or higher component: By adjusting the mixing ratio in the range of 70 to 90% by weight and controlling the melting point and freezing point in each microcapsule, the temperature can be adjusted to any design temperature range within the above design temperature range. Thus, the mixing ratio that maximizes the phase change efficiency (the maximum heat of fusion and solidification) can be adjusted in the microcapsule.

Further, by mixing other molecular weight inclusions with the latent heat storage material in the core material, it is possible to correspond to an arbitrary heat exchanger temperature condition corresponding to the design temperature range.

[0070]

According to the present invention, it is possible to provide a heat storage material capable of appropriately controlling the freezing point and the melting point, and capable of storing and releasing heat by effectively utilizing the heat of solidification and the heat of fusion.

According to the present invention, the operation of the freezing point and melting point can be appropriately performed within the cold water design temperature range,
In addition, it is possible to provide a heat storage material that can effectively use heat of solidification and heat of fusion in a narrow temperature range and can store and release heat.

According to the present invention, it is possible to provide a heat storage material that can cope with any heat exchanger temperature condition corresponding to the cold water design temperature range.

According to the present invention, it is possible to provide a heat storage material capable of storing and releasing heat using cold water having a large temperature difference.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a latent heat storage system to which a microcapsule slurry as a heat storage material according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a temperature response characteristic during melting and a temperature response characteristic during solidification of the heat storage material according to the embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between temperature and specific enthalpy of the heat storage material according to the embodiment of the present invention.

FIG. 4 is a diagram showing the concentration and phase change efficiency of tetradecane and pentadecane according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between temperature and specific enthalpy in the heat exchanger when the weight ratio of the latent heat storage material according to the embodiment of the present invention is large.

FIG. 6 is a diagram showing a relationship between temperature and specific enthalpy in the heat exchanger when the weight ratio of the latent heat storage material according to the embodiment of the present invention is small.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heat storage tank 11 ... Microcapsule slurry 2 ... Heat exchanger 3 ... Slurry circulation circuit 4 ... Cold water circulation circuit 5 ... Refrigerator 51 ... Evaporator 52 ... Compressor 53 ... Condenser 6 ... Slurry pump 7 ... Cold water pump 8 ... Cold water pump 9 ... Cooling tower 10 ... Cooling water pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Akira Fukuda, Inventor, 24, Kinone Jindai, Narita, Chiba Prefecture Inside the New Tokyo International Airport Corporation (72) Inventor, Tadashi Tsuno 24, Kinone Jindai, Narita, Chiba, Japan (72) Inventor Toshihiro Suzuki 24, Kinone Jindai, Narita City, Chiba Prefecture New Tokyo International Airport Corporation (72) Inventor Toshio Tashiro 24, Kinone Jindai, Narita City, Chiba Prefecture New Tokyo International Airport Corporation (72) Inventor Takao Yokose 24, Kinonejidai, Narita-shi, Chiba Pref. Inside the New Tokyo International Airport Corporation (72) Inventor Seiji Shibuya 2-1-1, Aramachi-cho, Niihama, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 2-1-1 Niihama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Works, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yoshinori Shirakata Niihama, Arai-machi, Takasago City, Hyogo Prefecture 2-1-1, Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Yoichiro Iriya 2-1-1, Araimachi, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Tadaaki Yai Takasago, Hyogo Prefecture 2-1-1, Niihama, Araimachi Inside the Takasago Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Mika Shinka 2-1-1, Niihama, Araimachi, Takasago-shi, Hyogo Prefecture Inside the Takasago Laboratory, Mitsubishi Heavy Industries, Ltd.

Claims (5)

[Claims] 1. A heat storage material used as a slurry in which a core material with a phase change is enclosed in a fine capsule made of an organic film material, wherein the core material is at least two kinds of aliphatic hydrocarbons having different molecular weights. A heat storage material characterized by comprising a mixture of: 2. The core material comprises, as a main constituent, a mixture of tetradecane and pentadecane, which are aliphatic hydrocarbons.
In the core material, the main constituent material has a weight ratio of 80% or more, and the mixing weight ratio of the tetradecane and the pentadecane is 30 to 10% for the tetradecane and 70 to 90% for the pentadecane. The heat storage material according to claim 1, wherein a solidification point and a melting point are made to correspond to an arbitrary design temperature range by controlling a weight mixing ratio of a main constituent substance of the core substance. 3. The core material is an industrially purified product mainly composed of a mixture of high molecular components mainly composed of aliphatic hydrocarbons tetradecane and pentadecane. The weight ratio of the tetradecane and the polymer component containing pentadecane as a main component is 80% or more. The molecular component is 70 to 90%, and the high molecular component containing hexadecane or more is 10 to 15%.
2. The heat storage material according to claim 1, wherein a solidification point and a melting point are made to correspond to an arbitrary design temperature range by manipulating a weight mixing ratio of a main constituent substance of the core substance. 3. . 4. The core material is a refined product for industrial use, which is mainly composed of a mixture of high molecular components mainly composed of aliphatic hydrocarbons tetradecane and pentadecane. It has a weight ratio of 80% or more, and expands the phase change range in the design temperature range by interposing a molecular weight substance other than the core substance to obtain an effective temperature difference in an arbitrary heat exchanger. The heat storage material according to claim 1, 5. The heat storage material according to claim 2, wherein said design temperature range is a range from a feed temperature of cold water of 2 ° C. to a return temperature of 15 ° C.